Some displays incorporate backlights comprising arrays of light-emitters that can be individually controlled. Light from the backlight is modulated by a spatial light modulator (‘SLM’) such as an LCD panel to display images. Such displays can provide the advantage of increased contrast since the backlight may be locally dimmed in regions where an image is dark.
Some non-limiting examples of displays in which the amount of light incident on a spatial light modulator can be controlled are described in the following patents and patent applications:                U.S. Pat. No. 6,891,672 issued 10 May 2005 and entitled High Dynamic Range Display Devices;        U.S. Pat. No. 7,403,332 issued 22 Jul. 2008 and entitled High Dynamic Range Display Devices;        United States Patent publication No. 2008/0180466 published 31 Jul. 2008 and entitled Rapid Image Rendering on Dual-modulator Displays;        PCT Publication No. WO 2002/069030 published 6 Sep. 2002 and entitled High Dynamic Range Display Devices;        PCT Publication No. WO 2003/077013 published 18 Sep. 2003 and entitled High Dynamic Range Display Devices;        PCT Publication No. WO 2005/107237 published 10 Nov. 2005 and entitled Method for Efficient Computation of Image Frames for Dual Modulation Display Systems Using Key Frames;        PCT Publication No. WO 2006/010244 published 2 Feb. 2006 and entitled Rapid Image Rendering on Dual-Modulator Displays.        PCT Publication No. WO 2006/066380 published 29 Jun. 2006 and Entitled: Wide Color Gamut Displays; and        PCT Publication No. WO 2008/092276 published 7 Aug. 2008 and entitled: Calibration of Displays Having Spatially-Variable Backlight;all of which are hereby incorporated herein by reference for all purposes.        
A backlit local dimming or dual modulator type display needs to have some mechanism for controlling elements of the backlight. It is desirable that the backlight be controlled in a manner that yields good quality images. At the same time, cost is an issue and so it is desirable to achieve control over backlight elements with less expensive hardware.
Ward et al., WO 2005/104035 (“Ward”) published on 3 Nov. 2005 and entitled Encoding, Decoding and Representing High Dynamic Range Images describes a format that may be used for encoding high dynamic range images. The format provides a first part that contains a lower dynamic range version of an image and a second part that contains information that can be used to modify the lower dynamic range version of the image to recover a high dynamic range version of the image. Ward is hereby incorporated herein by reference for all purposes.
There remains a need for efficient ways to display images on displays having local-dimming backlights and for cost-effective local dimming displays that can provide good quality images.
Unless otherwise indicated, the reference to any approach or document in this section is not an admission that the approach or document constitutes prior art.